西双版纳热带季节雨林优势树种树干呼吸特征

 采用红外气体分析法（IRGA）原位监测了西双版纳热带季节雨林11种优势树种树干呼吸速率、1 cm深树干温度以及林内空气变化情况。研究发 现，11种优势树种的树干呼吸具有相同的季节规律，并且雨季均大于干季时的树干呼吸。树种间树干呼吸速率差异显著，在0. 823～2.727 μmol&;#8226;m^-2&;#8226;s^-1。树干1.3 m处所测南北方向树干呼吸无显著性差异。树干呼吸与树干温度显著相关(0.552<0.92)，呈良好的自然指数回归关 系，Q₁₀值为1.90～3.03。20 ℃时各树种的RT（总树干呼吸）速率为0.771～2.570μmol&;#8226;m^-2&;#8226;s^-1。

STEM RESPIRATION RATES OF DOMINANT TREE SPECIES IN A TROPICAL SEASONAL RAIN FOREST IN XISHUANGBANNA, YUNNAN, SOUTHWEST CHINA

Aims Forest is an important pool of carbon in terrestrial ecosystems. Woody tissues contribute much biomass, and their respirations influence carbon fixation. Stem respiration is an important component of the carbon budget of forest stands. Stem respiration has been studied in temperate and boreal zones, but seldom has been reported for tropical rain forests. Our objective was to investigate the characteristics of stem respiration and the response of stem respiration to temperature in 11 common trees in Xishuangbanna tropical seasonal rainforest. Methods We made in situ chamber measurements of stem respiration using an Li-820 infrared CO₂ gas analyzer (IRGA) from March 2005 to February 2006. Our custom-built polyvinyl chloride (PVC) chamber sealed to the stem by thin neoprene gaskets. Stem respiration rates were measured on south and north sections at 1.3 m height, and stem temperatures were recorded at 1 cm depth. Important findings Stem respiration rates of all species had similar seasonal patterns and were higher in the wet season and lower in the dry season. There were significant differences in stem respiration rates among species, ranging from 0.823 to 2.727μmol&;#8226;m^-2&;#8226;s^-1. Stem respiration rates on the south and north sections were similar for the same species. Significant exponential correlations w ere observed between stem respiration rates and stem temperatures (0.55＜R²＜0.9 2). Q₁₀ values for stem respiration among species ranged from 1.90 to 3.03, somewhat higher than the range (1.6-2.38) reported in previous studies.